My reason to flyfish changes almost daily. Everynow and then i get in the mood to just go put a serious woopin on some trout, and i go up high, and just catch trout till im blue in the face. Size makes no difference on those days, it about numbers, and i suppose deep down inside, about feeling superior ( i guess our apposable thumbs versus trout only having fins just isnt superior enough some days).
Then there are the days where flyfishing is an excuse, and a good one, to get out of the house, in to God's creation and wonder about its perfection. On those days fishing takes a back seat, and any fish caught are marveled at as rare jewels, or priceless art. The perfect cast, and right drift become as important as actually catching fish, and often, the casts are far and few between.
For whatever the reason however one thing always stays the same. Im never happier than when I am on a stream. And the only time im not thinking about fishing, is when im doing it...